1. Field of the Invention
The invention relates generally to methods and 15 apparatus for generating a signal for controlling engine operation, and more particularly to methods and apparatus for generating a control signal corresponding to rotation of a component of an engine.
2. Related Prior Art
It is generally known to measure the speed of a rotating member by generating and monitoring an electrical signal corresponding to the speed of the rotating member. One common method for generating such a signal is to fix a sprocket on the rotating member so that the teeth of the sprocket rotate in a plane perpendicular to the axis of rotation, and to provide a magnetic field and a conductor in the proximity of the sprocket. Rotation of the sprocket teeth through the magnetic field induces an electrical current in the conductor, and the frequency of the current will correspond to passage of the teeth through the magnetic field. The frequency of the current, in combination with the known angular spacing of the teeth, provides sufficient information from which the average rotational speed of the member can be calculated over a known period of time.